Hi,
here is a patch in two versions, one for mainline and
the second for SLES11 SP1. I don't know, whether this
is the best solution, but the version for SLES11 fixes
the problem for me. It already is tested for about 12
hours and I just started the test again to have it run
for the entire weekend.
The patch for mainline is untested.
Bodo
################################
From: Bodo Stroesser <bstroesser@xxxxxxxxxxxxxx>
Date: Fri, 15 Mar 2013
Subject: [PATCH] net: sunrpc: fix race in RPC cache
This patch applies to linux-3.7.6 plus 2 earlier
patches that also fix races
If between a thread's calls to sunrpc_cache_lookup()
and cache_check() the cache entry returned by lookup
is modified by
a) sunrpc_cache_update() setting expiry_time is set to 0
b) cache_clean() unhashing it, as it now is expired
then the thread will perform an upcall for the outdated
cache entry. That cache_request will stay on the queue
for ever, as a reply to the request will always match
a newer cache entry and the request isn't dequeued.
OTOH, cache_clean() already unhashed the old entry, thus
cache_clean() won't dequeue the request also.
To fix the problem, in cache_check() we recheck the state
of the cache entry after having set CACHE_PENDING. So we
are sure to never do an upcall for an outdated entry.
Signed-off-by: Bodo Stroesser <bstroesser@xxxxxxxxxxxxxx>
---
--- a/net/sunrpc/cache.c 2013-03-15 21:14:54.000000000 +0100
+++ b/net/sunrpc/cache.c 2013-03-15 21:29:09.000000000 +0100
@@ -222,6 +222,17 @@ static inline int cache_is_valid(struct
}
}
+static inline int cache_wants_upcall(struct cache_head *h, int final)
+{
+ long refresh_age = (h->expiry_time - h->last_refresh);
+ long age = seconds_since_boot() - h->last_refresh;
+
+ if (final)
+ dprintk("RPC: Want update, refage=%ld, age=%ld\n", refresh_age, age);
+
+ return h->expiry_time && age > refresh_age/2;
+}
+
static int try_to_negate_entry(struct cache_detail *detail, struct cache_head *h)
{
int rv;
@@ -255,24 +266,22 @@ static int try_to_negate_entry(struct ca
int cache_check(struct cache_detail *detail,
struct cache_head *h, struct cache_req *rqstp)
{
- int rv;
- long refresh_age, age;
+ int rv, rc;
/* First decide return status as best we can */
rv = cache_is_valid(detail, h);
- /* now see if we want to start an upcall */
- refresh_age = (h->expiry_time - h->last_refresh);
- age = seconds_since_boot() - h->last_refresh;
-
if (rqstp == NULL) {
if (rv == -EAGAIN)
rv = -ENOENT;
- } else if (rv == -EAGAIN || age > refresh_age/2) {
- dprintk("RPC: Want update, refage=%ld, age=%ld\n",
- refresh_age, age);
+ } else if (rv == -EAGAIN || cache_wants_upcall(h, 0)) {
if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
- switch (cache_make_upcall(detail, h)) {
+ rv = cache_is_valid(detail, h);
+ if (rv == -EAGAIN || cache_wants_upcall(h, 1))
+ rc = cache_make_upcall(detail, h);
+ else
+ rc = -EAGAIN;
+ switch (rc) {
case -EINVAL:
rv = try_to_negate_entry(detail, h);
break;
################################
From: Bodo Stroesser <bstroesser@xxxxxxxxxxxxxx>
Date: Fri, 15 Mar 2013
Subject: [PATCH] net: sunrpc: fix race in RPC cache
This patch applies to linux-2.6.32.59-0.7.1.4543.0.PTF
plus 2 earlier patches that also fix races
If between a thread's calls to sunrpc_cache_lookup()
and cache_check() the cache entry returned by lookup
is modified by
a) sunrpc_cache_update() setting expiry_time is set to 0
b) cache_clean() unhashing it, as it now is expired
then the thread will perform an upcall for the outdated
cache entry. That cache_request will stay on the queue
for ever, as a reply to the request will always match
a newer cache entry and the request isn't dequeued.
OTOH, cache_clean() already unhashed the old entry, thus
cache_clean() won't dequeue the request also.
On this older SW version, the problem additionally leads
to RPC requests being dropped.
To fix the problem, in cache_check() we recheck the state
of the cache entry after having set CACHE_PENDING. So we
are sure to never do an upcall for an outdated entry.
Signed-off-by: Bodo Stroesser <bstroesser@xxxxxxxxxxxxxx>
---
--- a/net/sunrpc/cache.c 2013-03-15 20:03:54.000000000 +0100
+++ b/net/sunrpc/cache.c 2013-03-15 20:14:13.000000000 +0100
@@ -184,7 +184,7 @@ static int cache_make_upcall(struct cach
static inline int cache_is_valid(struct cache_detail *detail, struct cache_head *h)
{
if (!test_bit(CACHE_VALID, &h->flags) ||
- h->expiry_time < monotonic_seconds())
+ (h->expiry_time && h->expiry_time < monotonic_seconds()))
return -EAGAIN;
else if (detail->flush_time > h->last_refresh)
return -EAGAIN;
@@ -197,6 +197,17 @@ static inline int cache_is_valid(struct
}
}
+static inline int cache_wants_upcall(struct cache_head *h, int final)
+{
+ long refresh_age = (h->expiry_time - h->last_refresh);
+ long age = monotonic_seconds() - h->last_refresh;
+
+ if (final)
+ dprintk("RPC: Want update, refage=%ld, age=%ld\n", refresh_age, age);
+
+ return h->expiry_time && age > refresh_age/2;
+}
+
/*
* This is the generic cache management routine for all
* the authentication caches.
@@ -214,24 +225,22 @@ static inline int cache_is_valid(struct
int cache_check(struct cache_detail *detail,
struct cache_head *h, struct cache_req *rqstp)
{
- int rv;
- long refresh_age, age;
+ int rv, rc;
/* First decide return status as best we can */
rv = cache_is_valid(detail, h);
- /* now see if we want to start an upcall */
- refresh_age = (h->expiry_time - h->last_refresh);
- age = monotonic_seconds() - h->last_refresh;
-
if (rqstp == NULL) {
if (rv == -EAGAIN)
rv = -ENOENT;
- } else if (rv == -EAGAIN || age > refresh_age/2) {
- dprintk("RPC: Want update, refage=%ld, age=%ld\n",
- refresh_age, age);
+ } else if (rv == -EAGAIN || cache_wants_upcall(h, 0)) {
if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
- switch (cache_make_upcall(detail, h)) {
+ rv = cache_is_valid(detail, h);
+ if (rv == -EAGAIN || cache_wants_upcall(h, 1))
+ rc = cache_make_upcall(detail, h);
+ else
+ rc = -EAGAIN;
+ switch (rc) {
case -EINVAL:
write_lock(&detail->hash_lock);
if (rv) {
ÿôèº{.nÇ+?·?®??+%?Ëÿ±éݶ¥?wÿº{.nÇ+?·¥?{±þwìþ)í?æèw* jg¬±¨ ¶????Ý¢jÿ¾«þG«?éÿ¢¸ ¢·¦j:+v?¨?wèjØm¶?ÿþø ¯ù ®w¥þ?àþf£¢·h??â?úÿ?Ù¥
